First topic was locked!
As preloading is quite difficult to realize (Leo) maybe the speed could be a bit increased if DO just wouldn't always load the full picture when swichting to next.
What do you mean by "load the full picture"?
When scrolling through pics, for example from pic 1 to pic 3, pic 2 will be loaded before showing pic 3. Sometimes I can see the full pic for less than a second, mostly I see a blank screen before next pic is shown. Also when switching >3 pics, it takes 2+ sec before next pic is shown. So I think, DO always tries to load each pic.
This and slow loading of a picture is the point. With ACDSee there's NO such delay, really.
if it's so important for you to save a few hundred milliseconds when viewing images, then it would make sense to use an app that is designed for viewing images, rather than a general-purpose file viewer. as such, if you find acdsee to be better suited to your needs, then why don't you just use acdsee? i don't understand all the fuss...
Why using x tools if DO could do so (just showing pictures, not editing - it's a filemanager which supports also Flickr!). That's why the fuss...
There's no need to comment if you're not interested 
Also not millisecs... the more pics I skip the longer DO needs to show - if you would carefully read you would have understand!
I still find that a bit confusing as it sounds like you're saying that Opus does not currently load the entire picture, yet somehow displays the picture. 
I guess you mean that Opus should continue displaying the old picture until the new one is ready? I don't think I've ever noticed the screen going blank between images (but maybe it does and I just haven't noticed it) but changing that would be about as much work as adding pre-loading, so it'd be better to put that effort into adding pre-loading instead.